Welding apparatus



y 1943- w. A. WEIGHTMAN 2,323,696

WELDING APPARATUS Original Filed. Dec. 7, 1940 5 Sheets-Sheet 1 V, uunnnmnn I IIIIIIIIIII I N V EN TOR W imam AWeLg htman A TTORNEY y 1943- f v w. A WEIGHTMAN 2,323,696

WELDING APPARATUS Original Filed Dec. 7, 19.40 s Sheets-Sheet 2 /NVENTOR W'LLhamAWe'Lghcman.

A TTORN E Y July 6, 1943- A. WElGHTMAN 2,323,696

I WELDING APPARATUS Original Filed Dec. 7, 1940 5 sheets-sheet 3 INVIENTOR William Qweiqhc'man.

1 ATTORNEY w.i .WEIGHTMAN wnwme APPARATUS July 6, 1943.

Original Filed Dec. 7, 1940 5 Sheets-Sheet 4 I b ..W

w a a. i: M

INVENTOR William Aweightman.

AT TORNEY July 6, 1943. x

W. A. WEIGHTMAN WELDING APPARAT S Original Filed Dec. 7, 1940 5 Sheets-Sheet Z 1:: \l MA ATTQRNEY Patented 6, 1943 i UNITED STATES- PATENT. OFFICE wammc msnsrus William .A. Weightman. Philadelphia, 1a.. assignor to'Edward G. Budd Manufacturing Company, Philadelphia, sylvania la., a corporation of Penn- Original application December '1, 1940, Serial No..

Divided and this application November 10, 1941, Serial No. 418,477

9 Claims. (Cl. 219-4) This application is a division of my copending application Serial No. 369,007, filed December 'I, 1940, issued as Patent No. 2,313,789, March 16, 1943, for Welding apparatus.

. This invention relates to multiple spot welding apparatus and more particularly to apparatus for eflecting a large number of welds in workpieces of irregular shape at a high rate of speed.

In spot welding a flanged seam between adjacent members it is essential that a plurality of welds be arranged with relatively close spacing since the welds are generally in,tension and a plurality are requiredfor strength. Where such a seam is located within a concavecurve a great amount of difiiculty is encountered in providing a plurality of welding guns side by side and suiii cientiy closely spaced particularly in such curved portions since the guns ordinarily would interfere with one another. Also considerable difliculty is encountered in providing suitable mechanism for clamping the workpieces in welding position since the clamps must be clear of interierence with the welding guns. In addition, such clamping mechanism must be capable of quickly securing and releasing workpieces to the end that upon the completion of a large number of welds at high speed the apparatus may be unloaded and loaded It is accordingly an object of the present invention to provide a series of closely spaced pairs of welding electrodes such that they may embrace adjacent flanges to eflect closely spaced spot welds along the length thereof.

Another object of the invention is to provide such electrodes arranged at such an angle that they may project into a concave curved portion,

. with a new set of workpieces in a'minimum'oi time.

the central electrode in themiddle of the concave portion being substantially normal to the line of welds at the point.

A further object of the invention is to provide a novel work support so arranged with respect the section is takenexcept through the welding to a series of electrodes arranged along a line as to permit-the swinging of a workpiece about a pivot into position with respect to the electrodes for welding. Y

Still another object of the invention is to providenovel clamping means for securing workpieces within a work holder such that the workpieces may be quickly clamped in place and quickly released upon completion of the welding operation.

A yet further obiect of vide automatic sequential operation of such a welding apparatus such that upon loading the the invention isto pro-' I together by a longitudinal seam formed workpieces within the work holder, the same may be quickly moved to welding position, welds efiected and thereafter quickly removed from the machine. p

And still a further object of the invention is to provide'a welding tool adapted for, alignment with a plurality of other welding tools in stepped manner'and in which the welding pressure is applied from opposite sides to pinch the welding electrodes against a pair of continuous flanges and in which current is distributed to all the electrodes from a common source immediately to the rear of the electrodes.

4 The above and other novel features of the invention will appear more fully hereinafter from the following detailed description when taken in conjunction with the accompanying drawings. It is expressly understood, however, that the drawings are employed for purposes of illustration only and are not designed as a definition or the limits of the invention, reference being had for this purpose to the appended claims.

Referring to the drawings wherein like reference characters indicate like parts:

Figure 1 illustrates a pair of stampin'gs Joined by mating inside flanges.

Figure 2 is a-side elevation of the apparatus adapted to effect a plurality of welds along a flanged seam as indicated in Figure 1, the machine being shown in loaded but not welding position.

Figure 3 is a side elevation of the apparatus illustrating the machine in welding position.

Fi ure 4 is a section taken substantially on the line 4-4 of Figure 2 illustrating the manner of loading the machine.

Figure 5 is a transverse section taken substantially on the line 5-! of Figure 3, the section being transverse to the seam at the point where guns or substantially that portion which is shown enlarged in Figure 8 where the section is inclined. Figure 6 is anienlarged elevation of a welding gun parts of which are shown in section.

Figure '7 is a broken section through the axis of the welding gun of Figure 6 taken substantially on the line 1-].

Figure 8 is a broken section taken through the pivotssnd axis of the gun of Figure 6 substantiallyonthelinel-iofFlgurefl.

Figure 9 is an enlarged fragmentary side elevation illustrating a plurality of welding guns in Figure 3 adapted to eflect lap welds in the nose of-the stamping at the upper right hand portion thereof, parts of the frame structure being removed and parts of the stampings being cut away to illustrate the detail.

Figure 10 is an enlarged top plan view of a pair of electrodes of Figure 9, parts of which are shown in section.

Referring to Figure 1 there is illustrated a pairof stampings I and I2 having a longitudinal central seam I4 therebetween. The greater portion of the seam I4 is formed from a pair of mating flanges (see Figure 5), I8 and I8 extending to the point at the nose f the stampings at which point one stamping l2 has a portion 22 overlappin a portion 24 of the stamping I0 (see Figure 10). All along the length of the flanges I6 and I8 spot welds are to be effected at fairly uniformly spaced intervals and in the overlapped portions 22 and 24 in the nose a plurality of welds are to be eifected to form a lap joint thereat. The stampings are also provided with a plurality of apertures 25, 28 adapted to engage pins in the work holder of the machine in order to secure the parts in proper juxtaposition for welding.

In the apparatus shown in Figure 2 there is a base 30 having an upright column 3| upon which is pivotally mounted a work support 32, the same being pivotally mounted upon the column 3| at 34. The work support 32 is adapted to receive and hold a pair of stampings l0 and I2 such as illustrated in Figure 1. arranged a diagonal frame member 36 from which are supported a plurality of welding guns 30 adapted to effect welds along the length of the seam formed by the flanges I6 and I8. A top framework 40 is provided adapted to brace th diagonal frame 36 and support a fluid pressure distributing unit 42 to supply fluid pressure sequentially to various guns or sets of guns.

The work support 32 comprises a base member 44 upon which is arranged a central I-beam 45 against which the members I2 and I0 and the seam flanges I6 and I8 are positioned during welding. In order to secure the workpieces in proper position, the L-beam rest 46 is provided with a series of pins 52 and 54 adapted to engage the apertures 28 in the stampings I0 and I2 so as to assure proper positioning of the parts. To hold the stampings in position after having been properly placed in the work support, a plurality of clamps 56 are provided, the clamps being operated by fluid pressure and being adapted to grip the marginal flange 53 of the stampings I0 and I2. Each of the clamps comprises an upright 60 having abutments 62 and 64 at the top thereof for receiving the marginal flange 58. The abutment 62 is rigidly secured to the upright 60 and has a face 66 especially shaped to receive the workpiece l2. The abutment member 54 likewise is provided with a face 60 to engage the marginal flange of the workpiece I2 and is pivoted upon the abutment member 62 at the point I0 as indicated. In order to positively hold the marginal flange oi the workpiece I2 in proper engagement with the abutment members 62 and 64 and the faces 66 and 68 thereon, a clamping member 12 is provided, the same being slidably secured upon the pivotal abutment member 64. The clamping member 12 has an overhanging abutment 14 adapted to engage the workpiece I2 from the opposite side of the abutment faces 06 and 00 near the marginal flange so that when the member 12 is slid upon the abutment member 64 to the pofltion shown in Figure 5, the workpiece I: is positively secured in position and Upon the upright 3| is against any possible movement. As indicated in Figure 5 the sliding movement of the member 12 upon the member 64 is arranged for through the bolt 16 extending through the slot 18 in the member I2 and by reason of the slotted tail portion 19 of the member 12 through which a pin 8| extends, the pin being secured in upstanding ears 83 on the abutment block 04 on either side of the tail portion 19.

In order to operate the clamping mechanism a fluid pressure cylinder is secured to the upright member 60, the fluid pressure cylinder acting through a piston 82 upon a linkage B4 and toggle mechanism 86, the latter of which is pivoted at one end upon the pin ill and at the other end upon a pin 88 in the sliding member 12.

Thus upon exerting a force upon the knee 90 of the toggle through the linkage 84 the toggle is caused to straighten or. to the position indicated in dotted lines in Figure 5, sliding the clamping member 12 away from the marginal flange of the workpiece I2 and thereafter urging both the abutment member 64 and the slidable clamping member I2 angularly upward and out of the way so as to permit free unloading or loading of the work support. ,To limit the movement of the toggle when in the straightened out position, a stop 92 is provided on the slidable member 12 which is adapted to engage th toggle when in its straight position. It will thus appear that by admitting fluid pressure to the upper end of the cylinder the piston is driven downward, the toggle caused to bend and the clamping member 12 caused to slide so as to secure the marginal flange of a workpiece tightly into engagement with the abutment faces 66 and 88. On the other hand, admission, of fluid pressure to the lower end ofthe cylinder raises the piston and causes the release of the marginal flange of the workpiece through the lifting of the abutment face 68 as well as th clamping member 12.

The work support 32, as is illustrated in Figure 3, is adapted to be lifted around its pivot point 34 upward into an angular position so as to bring the workpieces and the flanges which are adapted to form the seam between the workpieces into position with respect to the welding electrodes 33. Such movement of the work support is effected through fluid pressure motors 94 acting between the base member 30 of the frame and lugs 96 upon the work support 32. When lifted into proper position, the outer end 98 of the work support 32 is adapted to engage a latch abutment member I00 depending from the frame 36, the abutment member carrying thereon a fluid pressure operated latch I02 adapted to engage the end 38 01' the work support 32 so as to retain the same in elevated position during the welding operation.

The welding guns 38 are supported from a pair of spaced bars I04 and I08 extending from the frame 36 to the abutment member I00 and are provided with suitable curvature as at I00 so that the welding guns mounted thereon will be adapted to engage the curved flanges IG' and I0 of the workpieces I0 and I2. The guns 3B are substantially identical and are supported from the bars I04 and I06 upon a general U-shaped depending bracket I I0, the lower portion of which is composed of spaced members I I2 and I I4 having a spacer II5 between which the moving parts of the welding gun are positioned. At the lower end of the U there is provided a pivot pin IIB extending between the members H2 and H4 and upon which are pivotally arranged the welding electrode holders Ill and I20, the electrode holders being nested upon the pin, and ining electrode holder members suitably offset so that the side by side position of the electrode holders upon the pin III is compensated for and the'electrodes I24 and I20 positioned in suitable alignment. -Also mounted upon'the pin IIB (see Figures 7 and 8) are electrical connecting members I28 and I00, the same being adapted to abut against the electrode holding members I I8 and I20 upon the planes of contact I02 and I34. At the same time, a sleeve extension of each of the connecting members I28 and I together with hearing rollers I88 and m provide an anti-friction bearing for the welding electrode holder members 8 and I20. Actuation of each of the welding'electrodes is ac-' complished through the operation of a fluid pressure cylinder I40 having a piston I42 therein, the cylinder being pivoted upon a pin I44 extending between the members H2 and H4 and the piston having an insulated extension I46 with a forked end I40 pivoted to each of the weld- II8 and I20 through a pin I00. The piston is provided with a radially extending lug I52 to which is secured a shouldered pin I84 extending parallel with the axis of the cylinder. Arranged upon the pin I84 is a return spring I50 compressed between the shoulder I88 on the pin I54 and a lug I88 on the Y cylinder through which the pin Il4 slidably extends. Return movement of the piston I42 is limited by a stop I02 arranged in the end of the As will be seen in Figure 10. each of the welding electrodes I88 is composed of an electrode tip holder I08 insulatingly mounted upon' a piston rod I88 having a piston 200 thereon acting in a cylinder bore 282 in the supporting member I00. An extending sleeve 204 threadedly secured in the bore 282 is provided together with a bearing block 200 for the purpose of accurately guiding the movement of the welding electrode as well as housing a return spring 208 within the sleeve and around the rod I80, the spring bearing against the block 208 and the piston 200. Since it is desirable that the electrode tips 2I0 be offset from the center in order to effect welds extremely close together, relative rotation between the rod I88 and, cylinder bore 202 is preferably prevented in any-suitable manner as by a key between the block 208 and the rod I08, not shown however.

The welding electrodes, therefore, will appear to be arranged in two groups, one group being fed from the transformer I12 and the other group from the transformer I14.- All of the welding guns of one group'are permanently connected as will be appreciated across the bus bars and to the transformer. In order to effect a sequential operation of the welding guns, a fluid pressure distributor valve 2I2 is provided, the same being driven by a motor 2 and being adapted to suppiston I42 and adapted to abut the cylinder head Electrical connections are made to the contact members I30 and I28 through the flexible connections I86 to the water cooled bus bars I88 and I10, the latter extending parallel with the bars I04 immediately above the welding electrodes. Two transformers I12 and I14 are arranged in the frame 36, one of which supplies the first eleven guns from the left-hand side of the machine as seen in Figure 2. the bus bars I80 and I10 being broken between the eleventh and twelfth gun and connected to the transformer I12 through connecting bars I10 and I18, the bars I16 and I18 being connected to the bus bars I08 and H0 at their opposite ends so that equal electrical paths of flow of'welding current to any pair of guns from the transformer areprovided. The other transformer H4 is connected through a similar pair of bus bars I80 and Ill extending from the twelfth welding'electrode around the curve and terminating at their ends at I82 and I83. Opposite ends of these bus bars-are connected to the transformer I" through connecting conductors I84 and I88.

In order to effect a plurality of lap welds in the nose of theworkpiece formed by the stampbeing connected to one bar and an adjacent gun being connected to the other bar. To effect welds through these guns, two welds are made in series. For this purpose, conducting bridging blocks I02 are supported from the frame 30 upon a bracket I84-and are adapted to substantially fit the internal contour of the lapped portions 22 and. 24

of the workpieces I 0 and I2 when the work holder is in. elevated position as illustrated in Figures 3 3and9.

ply fluid pressure sequentially to the various welding guns. With the distribution of fluid pressure to each gun welding current is supplied to the welding transformers by means of a synchronized welding current control switch 2| 0 also driven by the motor 2, welding current being applied to the bus bars each time that a welding gun is supplied with fluid pressure from the distributor valve 2I2. The distributor valve is .composed of a casing as shown having secured around its exterior a plurality of valves such as 2I8. which valves are bolted to's'eats 220 on the casing, the valves being removed from the number of the seats in order to more clearly illustrate the invention. The particular structure of the distributor valve does not form a part of the present Invention but may have the same functional operation as that illustrated in my copending application Serial No. 143,600, filed May 19, 19311,,

I now Patent No. 2,229,993, January 28, 1941-. "'It will be appreciated that each of the valves 2 I 8 are connected to the cylinders I40 of a welding gun 88 or to a pair of cylinders 202 of the welding electrodes I88. If desired, one valve may supply fluid pressure to'a welding gun of the group supplied with current from the welding transformer I12 and simultaneously to a welding sun or pair of electrodes supplied with welding current from the transformer I14. By thus using a common valve for both groups, the entire set of welds are effected in the time of operation of a single group and if the welds are made at a rate not greater than one per second,,a complete set of welds will be completed in the course of eleven seconds.

The operation of the apparatus is to a large extent automatic. Upon the placing of a pair of workpieces I0 and I2 in the work holder, a manual valve 222 is operated to supply fluid pressure to the up er end of the cylinders so as to cause the fluid pressure operated clamps to grip and securely hold the work in place. Thereafter, the manual valve 224 may be operated to supply fluid pressure through the pipe line 220 to the 'work.

tion, the work holder engages a limit switch 228 which immediately energizes the motor 2| I setting the distributor valve 2 l 2 into operation. The welds are thereupon sequentially effected, and upon completion of the last weld, the distributor switch moves to a valve such as 2l8, which supplies fluid pressure to a latch actuating motor. 230 opening the latch I02 and at the same time, supplying fluid pressure to the pipe line 232 to the valve operating motor 234 associated with the manual valve 224 so as to supply fluid pressure to the upper end of the work elevating cylinders 94 to thereupon lower the work. At the same time the motor 2| 4 is cut off and the distributor valve thereby stopped. Release 0! the workpieces is then effected through the operation of the manual valve 222 which supplies fluid pressure to the underside of the piston in the fluid pressure motor 80 to release the clamps thereby permitting removal of the workpieces.

There is thus provided a multiple spot welding apparatus capable of effecting a plurality of closely spaced welds along a flanged seam at a rapid rate, and in which rapid loading and unloading of the workpieces is provided for. Further the apparatus is such as is adapted to reach into relatively close quarters as where the seam extends along the inside of a concavity.

Though a single embodiment of the invention has been illustrated and described, it is to be understood that the invention is not limited thereto, but may be embodied in various mechanical forms and combinations as may be desired. As various changes in construction and arrangement of parts may be made without departing fromthe spirit of the invention, as will be apparent to those skilled in the art. reference will be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

1. In a multiple spot welding apparatus, a frame comprising a base, a column thereon and an overhanging welding gun support member, said welding gun support member extending diagonally from said column upward, a plurality of substantially perpendicularly depending welding guns carried by said support member, said guns having welding electrodes positioned in substantially V-shaped formation adapted to effect welds having an axis substantially horizontal and transverse to said support member, and a work supporting member pivoted to said column movable from a lower loading position to an elevated welding position.-

2. In a multiple spot welding apparatus, a frame, comprising a support for a plurality of closely spaced similar welding guns, said frame comprising a pair of spaced substantially parallel support members, a plurality oi welding guns se-- cured to said parallel members in staggered arrangement, each gun including a U-shaped bracket comprising spaced plates, a pin extending between said plates, and a pair of welding electrodes pivoted on said pin, said plates being arranged at an angle to the adjoining portion of said support members.

3. In a multiple spot welding apparatus, a frame comprising a base, a column thereon, and an overhanging welding gun support member, a plurality of welding guns having cooperative electrodes depending from said member and a work supporting device associated with said frame, movable from a lower loading position to an elevated welding position, means for moving said work supporting device from the loading position to the welding position, means for securing said device in welding position and for initiating the eiIecting 01' a plurality of welds, and means acting upon the completion of the welds for releasing said securing means and lowering said supporting device to the loading position, the electrodes of said guns being angularly positioned with reference to the plan of movement or said work supporting device.

4. In a multiple spot welding apparatus a frame comprising a base, a column thereon, and an overhanging welding gun support member, said member extending diagonally from said column upward, a top frame member extending between said column and the upper end of the gun support member, a plurality of fluid pressure welding guns depending from said support member, a loading device pivoted on said column and adapted to swing from a substantially horizontal loading position to an inclined welding position adjacent to said depending welding guns and said diagonal member, welding transformers supported from said diagonal member, a fluid pressure distributing valve located on said top member, and means for sequentially delivering fluid pressure from said valve, and welding energy from said transformers to said welding guns, said welding nergy delivering means including a closed circuit bus bar in serie between the transformer and group of guns whereby the reactance from each gun to the transformer is equalized.

5. In a multiple spot welding apparatus, a frame comprising a base, and an overhanging support for a plurality of depending welding guns, 3. work supporting device associated with said frame and elevatable from a work loading and unloading position to an elevated welding position, said gun having welding electrodes positioned at an angle to each other and the direction of movement of the work whereby horizontal welds may be made on the work.

' 6. In a multiple spot welding machine, a horizontal base structure having front and rear ends, a welding gun support fixed to the rear end and extending over the front end to form a forwardly divergent opening above said base structure, at least one welding gun depending from said welding gun support, said gun having cooperating electrodes positioned in V-relationship to the vertical whereby welding may be effected on vertically positioned seams extending from curvilinear work.

7. In a multiple spot welding machine, a horizontal base structure having front and rear ends, a welding gun support fixed to the rear end and extending over the front end to form a forwardly divergent opening above said base structure and a plurality of welding guns depending in inclined relationship from said welding gun support, each of said guns having opposed electrode units movable in a common plane and mounted on a common pivot in staggered relationship.

8. In a multiple spot welding machine, a horizontal base structure having front and rear ends, a welding gun support fixed to the rear end and extending over the front end to form a forwardly divergent opening above said base structure and a plurality of welding guns depending in inclined relationship from said welding gun support, each or said guns having opposed electrode units movable in a common plane and mounted on a common pivot, said electrode units forming a substantially vertical V-shape with each other with the electrodesbeing adjacent the V-apex.

9. In a multiple spot welding machine, a frame comprising a base, a col hanging welding gun sup thereon. an overrt member, at least one welding gun having cooperating electrodes depending from said me er, a work support- 'ing device associated with said frame and movable from a lower loading position to an elevated welding position, means for moving said work supporting device from the loading position to the welding position, means for securing said device in welding. position and m initiating the 

